do I need PP for the new pitched roof over existing extension

11 Jul 2018
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United Kingdom

I am in process of replacing my existing flat roof with new pitched roof. After much thought, apex type pitched roof will be best option for this kind of structure. It is for kitchen extension at the back of the property. Photo attached.

Following are the measurements:

Length (from the main building): 5 meters

Width: 3 meters

Height from the top of the flat roof to the bathroom window: 42 inches. (about 3.5 feet)

I have rang council and over the phone they said, you dont need PP but the person who was answering my query was a call center presonal and was looking at planning portal website and interpreting it. I want to be 100% sure about this before I start work.

Any thoughts? I am attaching picture of the extension with lines over roof to show how the roof is going to be.


View media item 104800
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So a volume of 45 cubic feet-metres?
Sorry prob. a rookie question. How would you measure ?

I have found this guide which talks about permitted development. House Extension Guide.pdf

Alterations to a Roof The alterations to a roof are permitted development provided that:
• The result of the works does not exceed the height of the highest part of the existing roof. As this is multistory semi detached house, the "height of the highest part of the existing roof" meaning main building's roof ?
• No works extend beyond the plane of any existing roof slope, which forms the principal elevation of the dwelling or fronts a highway.
• The new cubic content of the roof does not exceed 40 cubic metres in a terraced house or 50 cubic metres in any other case. - Is this only newly added roof space?
• The works do not consist of a veranda, balcony or raised platform.
Last edited:
You’re changing the roof of a previous extension... as in it’s not original?
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You’re changing the roof of a previous extension... as in it’s not original?
Yes thats right , its an extension build over 19 years ago with flat roof and I am changing it to pitched roof.
It's an alteration under Class B, and is Permitted Development as long as you don't go higher than the main house roof ridge or 50m3 in volume - which are the main things.

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